Benzene-derived carbon nanothreads

Low-dimensional carbon nanomaterials such as fullerenes, nanotubes, graphene and diamondoids have extraordinary physical and chemical properties(1,2). Compression-induced polymerization of aromatic molecules could provide a viable synthetic route to ordered carbon nanomaterials(3,4), but despite almost a century of study(5-9) this approach has produced only amorphous products(10-14). Here we report recovery to ambient pressure of macroscopic quantities of a crystalline one-dimensional sp(3) carbon nanomaterial formed by high-pressure solid-state reaction of benzene. X-ray and neutron diffraction, Raman spectroscopy, solid-state NMR, transmission electron microscopy and first-principles calculations reveal close-packed bundles of subnanometre-diameter sp(3)-bonded carbon threads capped with hydrogen, crystalline in two dimensions and short-range ordered in the third. These nanothreads promise extraordinary properties such as strength and stiffness higher than that of sp(2) carbon nanotubes or conventional high-strength polymers(15). They may be the first member of a new class of ordered sp(3) nanomaterials synthesized by kinetic control of high-pressure solid-state reactions.